목적: Acetylcholine (ACh) inhibits sensory hair cells of the inner ear. Calcium entry through the ACh receptor (AChR) triggers SK channel to hyperpolarize hair cells. A near-membrane postsynaptic cistern has been proposed to serve as a store from which calcium is released to supplement influx through the ionotropic ACh receptor. The purpose of this study was to examine the relative contribution of synaptic cistern to the activation of efferent inhibition. 방법:Whole-cell intracellular recordings were made on chicken short hair cell, decay & half-amplitude duration of SK tail-current at +40 mV can reflect the function of synaptic cistern. When calcium influx was terminated at positive membrane potential, the ACh-evoked potassium current decayed exponentially over~100ms. However, at negative membrane potentials, this current exhibited a secondary rise in amplitude that could be eliminated by dihydropyridine block of the voltage-gated calcium channels of the hair cell. 결과:Calcium entering through voltage-gated channels may transit through the postsynaptic cistern, since ryanodine and sarcoendoplasmic reticulum calcium-ATPase blockers altered the time course and magnitude of this secondary, voltage-dependent contribution to ACh-evoked potassium current. Electron microscopy showed that synaptic structures are juxtaposed, supporting the possibility that voltage-gated influx at afferent ribbon synapses influences calcium homeostasis during long-lasting cholinergic inhibition. In contrast, spontaneous postsynaptic currents (minis) resulting from stochastic efferent release of ACh were made briefer by ryanodine. 결론:The synaptic cistern serves primarily as a calcium barrier and sink during low-level synaptic activity. Hypolemmal cisterns such as that at the efferent synapse of the hair cell can play a dynamic role in segregating near-membrane calcium for short-term and long-term signaling.*Published in the Journal of Neuroscience, Dec 10 2014.